Weird that there’s no telnet with High Sierra. You could probably install it with homebrew.
I forgot to mention I used a voltage divider from the Roomba TX pin to the ESP12E RX pin since the Roomba serial is 5V and the ESP is 3.3V. I’ve read that the ESP is 5V tolerant but when I connected it directly I didn’t receive anything. I used a 5kOhm resistor and a 10kOhm resistor but anything above a few kOhm with a 1:2 ratio should be fine. So it’d be Roomba TX -> 5kOhm -> ESP rx -> 10kOhm -> GND.
@quasar66 check out my wake up method it’s doing what your recommend. The spec doesn’t say anything about the deep sleep that happens with the newer 650s while docked though. The Thinking Cleaner docs say it’s probably a bug in the Roomba firmware.